I have a 2001 S80 T6 and during the day I have no problems driving it, but around dusk I have received a low voltage warning message.

Day 1:
When this happened, I put a multimeter on the battery and it was reading 11.1, so I assume the alternator isn't working at that point. Shut the car off, and turned it back on after an hour of sitting and the warning was gone, tested the voltage again and it was reading 13.1V. Shut the car off and let it sit overnight.

Day 2:
Started the car up in the morning without issue, drove to work (30 miles) and around 30 miles during lunch, about 50 miles around dinner time. Around dusk again I get the low voltage warning, then Electrical System Service Required message. The battery icon was on at this point, which I hadn't seen until now.

Put the multimeter on the car again and it was reading 10.3V, tried to drive it home but made it about 1/8 mile and the car had died at this point. I parked the car and had it towed to an import garage in the area with a decent reputation.

Get a call from the garage today saying they couldn't find a problem...battery is good and alternator was charging the battery like it should. I went to the garage and started the car myself, no problems, no errors, nothing at all out of the ordinary...

Could it be that the alternator fails when there is a larger load on it at night? I don't want to just tell them to replace the alt. and then have this issue again.

Any suggestions would be much appreciated.

Thanks

 

To be clear- when you are driving the message appears? When the car is off everything is good the next day? Drive the car and eventually, while driving, the message appears?

 

Yes, exactly.

the voltage low warning comes on when driving for maybe about 30 minutes during dusk hours, the Elec System Service Required message also came on when driving the next evening around dusk after I got low voltage warning. In both cases I was driving for between 30 min and 1 hour. I can drive during the day for about the same period of time and not have an issue.

The car drives great and all electronics work as far as I can tell. No warning messages, unusual lights come on while driving during the day...The car always seems to start up the next morning.

Thanks for the reply and any suggestions!

 

Update:

Got a call from the shop, they said the car again started fine this morning and they didn't know what to tell me...

I asked them to please drive the car with everything they could think of turned on and running. They agreed and drove the car for about 45 minutes and the same thing happened to them, Low Voltage, Electrical System Service Required, battery light.

They towed the car back to the shop and threw it on the diagnostic equipment and found the alternator to be bad. They couldn't fix it today because of course the part didn't come in.

They will fix it July 5th and I'll post here again if I continue to experience any related problems.

 

got the car back tonight, they replaced the alternator and that seemed to fix the issue. I drove for about 3 hours with every accessory on, no problems.

cost:
$551.00 alternator
$190.00 labor on alt
$ 28.00 Headlight bulb
15.00 Labor on bulb
$ 75.00 Troubleshooting etc
so the job cost me around $850... way more than it cost me to put the alternator in my 1990 pontiac 6000 Seemed a little steep, even with a 12 month warranty on parts and labor...

the joys of volvo ownership..

 

dang, that is steep for the alternator. Did you get the Titanium edition? I would have expected closer to round $200, but I guess you have that autoshop mark-up on the parts too.